﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Demo01
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("请输入圆的半径(cm)");
            string r = Console.ReadLine();
            double radius = Convert.ToDouble(r);
            double area = 3.14 * radius * radius;
            Console.WriteLine("该圆的面积为" + area + "(cm²)");
        }
    }
}
